Alena Arshinova at the headquarters of Young Guard, the youth wing of Putin’s ruling United Russia party.

Alena Arshinova, 26, is running for a seat in the Russian parliament. A onetime model who loves yoga, vegetarianism and Mother Russia, she works with Molodaya Gvardiya (Young Guard), the youth wing of Prime Minister Vladimir Putin's ruling United Russia party. With her silken hair and telegenic teeth, she has become not just a leader of Young Guard but also something of a spokesmodel: her face is on T-shirts, and pictures of her hang throughout its Moscow headquarters.

But Arshinova is no empty vessel. She clawed her way from the backwater enclave of Transnistria, near Moldova, where she grew up, to...